These are just the poster children of bad covers. It's not a competition. Share your experiences so that we may understand.
Well, first and foremost are all the times I've been looking for a story with a female mc and clicked on a story with a girl or a woman on the cover only to find out it's a smut harem. It has happened too many times to count and I'm honestly tired of it.
On a more positive note, one of my favorite books of all time has a cover I could make myself in ten to twenty minutes. Basically a yellowish circle with the middle cut out so it looks like a moon, on a black background with some dots for stars and other smaller details. All in a single gradient of color, I think. It's unfortunately gone now (it's not showing up in searches on Scribble, at least) but it was called Celestial.
I'm sure there were a lot more of those, but I don't remember at the moment.